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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
    
    ol li:nth-child(even){
        color: green;
    }
    ol li:nth-child(odd){
        color: blue;
    }
    ol li:first-child{
        color: red;
    }


</style>
<body>
   <ul>
    <li>手机</li>
        <ol type="1" start="1">
            <li>iPhone14 Pro</li>
            <li>iPhone14</li>
            <li>iPhone13 Pro Max Plus</li>
        </ol>
    <li>平板</li>
    <ol type="1" start="1">
        <li>iPad Pro</li>
        <li>iPad</li>
        <li>iPad mini</li>
    </ol>
    <li>电脑</li>
    <ol type="1" start="1">
        <li>MacBook Pro</li>
        <li>MacBook Air</li>
        <li>iMac</li>
    </ol>
   </ul>
    
</body>
</html>